Granted Patent
Utility
US 4,742,538 · App. 07/008,344
Current source and off-hook detector
Inventor:
Aleksander Szlam
Patented Case
View Patent ↗
Granted: May 3, 1988
Filed: Jan 29, 1987
Inventor
Aleksander Szlam
Assignee (at issue)
Melita Electronic Labs, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.